refs #6: Optimize.

 * Uses the latest version of libev (4.2.22 instead of 4.2.15)

   - To use default settings, install it inside /usr/local.
     (Run ./configure --prefix=/usr/local && make && sudo make install)

   - This does not show significant performance changes.

 * Uses blocking calls to ev_run() when waiting for new batch objects
   available, and invokes ev_break() when we release batch objects.

   - This reduces excessive ev_run() polling overheads and improves the
     performance by 30%.  (Still, the absolute number is too low...)

 * Uses already-dynamic-casted references in scan_offloadable_elements().

   - This reduces CPU cycles used by scan_offloadable_elements(),
     but still no performance gains.

 * Tried no-opping GPU kernel execution, but it does not give
   any performance improvments.

   - This means that current bottleneck is not the computation itself.

3rdparty/libev/.gitignore

@@ -0,0 +1,9 @@
+.dep
+.deps
+.libs
+Makefile
+config.h
+config.log
+config.status
+libtool
+stamp-h1

3rdparty/libev/LICENSE

@@ -0,0 +1,37 @@
+All files in libev are
+Copyright (c)2007,2008,2009,2010,2011,2012,2013 Marc Alexander Lehmann.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+Alternatively, the contents of this package may be used under the terms
+of the GNU General Public License ("GPL") version 2 or any later version,
+in which case the provisions of the GPL are applicable instead of the
+above. If you wish to allow the use of your version of this package only
+under the terms of the GPL and not to allow others to use your version of
+this file under the BSD license, indicate your decision by deleting the
+provisions above and replace them with the notice and other provisions
+required by the GPL in this and the other files of this package. If you do
+not delete the provisions above, a recipient may use your version of this
+file under either the BSD or the GPL.

3rdparty/libev/Makefile.am

@@ -0,0 +1,20 @@
+AUTOMAKE_OPTIONS = foreign
+
+VERSION_INFO = 4:0:0
+
+EXTRA_DIST = LICENSE Changes libev.m4 autogen.sh \
+	     ev_vars.h ev_wrap.h \
+	     ev_epoll.c ev_select.c ev_poll.c ev_kqueue.c ev_port.c ev_win32.c \
+	     ev.3 ev.pod Symbols.ev Symbols.event
+
+man_MANS = ev.3
+
+include_HEADERS = ev.h ev++.h event.h
+
+lib_LTLIBRARIES = libev.la
+
+libev_la_SOURCES = ev.c event.c
+libev_la_LDFLAGS = -version-info $(VERSION_INFO)
+
+ev.3: ev.pod
+	pod2man -n LIBEV -r "libev-$(VERSION)" -c "libev - high performance full featured event loop" -s3 <$< >$@